<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .box {
      display: flex;
      background-color: #f00;
      width: 200px;
      height: 200px;
      flex-wrap: wrap;
    }
    .item{
      width: 60px;
      height: 60px;
      background-color: orange;
    }
  </style>
</head>

<body>
  aaa
  <div class="box">
    <div class="item">1</div>
    <div class="item">2</div>
    <div class="item">3</div>
    <div class="item">4</div>
    <div class="item">5</div>
    <div class="item">6</div>
    <div class="item">7</div>
    <div class="item">8</div>
    <div class="item">9</div>
  </div>
  bbb
</body>

</html>